Gaseous or fluorescent lamp systems normally employ a ballast system to compensate for abrupt impedance changes provided by the lamps when switched from one state of conductivity to another. Also, it has been known for some time that auto-transformer type ballast apparatus is relatively heavy, cumbersome, expensive and energy inefficient as compared with electronic ballast circuitry. Moreover, auto-transformer type ballast apparatus operates in the audible frequency range which is undesirable due to accompanying noises and disturbances annoying to the consumer.
Contrastingly, electronic ballast circuitry normally operates at relatively high frequencies, such as 20 to 30 KHz for example, which is well above the audible range and relatively free from undesired noise annoying to a consumer. Also, apparatus operating at such relatively high frequencies may be constructed smaller, less cumbersome and energy efficient as compared with auto-transformer apparatus.
Further, presently employed structures normally include a gaseous lamp fixture with either a two-lamp configuration and a single ballast circuit or a four-lamp configuration and a pair of ballast circuits. However, it is not uncommon for a two-lamp system to provide insufficient light and a four-lamp system to provide excessive light at a work surface. Thus, a three-lamp configuration is desirable but undesirably requires a pair of ballast circuits when commonly employed auto-transformers are utilized. Obviously, such apparatus is expensive with less than desirable energy efficiency.